1. Field of the Invention
The present invention relates to an ink delivery system for a liquid electrophotographic printer, and more particularly, to an ink delivery system for a liquid electrophotographic printer having a structure which enables recycling of a liquid carrier separated from ink supplied through an ink supplier.
2. Description of the Related Art
In general, in an electrophotographic printer, a latent electrostatic image is formed on a photosensitive medium such as a photoreceptor belt, by irradiating laser beams onto the photosensitive medium by a laser scanning unit (LSU), and then the latent electrostatic image is developed by supplying a developer liquid containing a toner mixed with a carrier, which is then transferred to a sheet of print paper.
As shown in FIG. 1, a conventional development apparatus includes a laser scanning unit (LSU) for forming an image corresponding to a latent electrostatic image on a photoreceptor belt 10, a drying unit 30 for drying a carrier remaining on the photoreceptor belt 10 after development, and an ink delivery system 40 for supplying a developer liquid of predetermined concentration and volume suitable for development, and recovering a carrier dried by the drying unit 30 after it is used in development.
The developer liquid is ink of a concentration of about 2.about.4 wt % obtained by mixing concentrated ink containing about 9 wt % powdered toner supplied from an ink cartridge 41 and a liquid carrier supplied from a carrier cartridge 43.
The ink delivery system 40 includes an ink cartridge 41 in which concentrated ink is stored, a carrier cartridge 43 in which a carrier is stored, a circulation tank 44 in which a developer liquid is stored, and a jet portion 47 for jetting the developer liquid to a development gap G between a development roller 21 for the development unit 20 and the photoreceptor belt 10 positioned corresponding thereto. The ink cartridge 41 includes an agitator 42 by which the concentrated ink accommodated therein is not precipitated, and is disposable, and can be replaced when the concentrated ink is used up. Also, the carrier cartridge 43 is disposable and can be replaced when the carrier contained therein is used up.
The circulation tank 44 is installed underneath the development unit 20, and supplies developer liquid to the development unit through the jet portion 47 and receives the residual developer liquid after being used for development so that the developer liquid is continuously supplied to the development gap G during development. A concentration sensor 45 for sensing the concentration of the developer liquid contained in the circulation tank 44, an upper limit level sensor 46a and a lower limit level sensor 46b, installed in the upper and lower portions of the circulation tank 44, for sensing the amount of developer liquid contained in the circulation tank 44, are installed in the circulation tank 44.
The jet portion 47 includes a jet path 47a through which the developer liquid is supplied, a jet pump 47b installed in the jet path 47a for pumping the developer liquid, and a nozzle 47c installed at an end near the development gap G for jetting the developer liquid to the development gap G.
The drying unit 30 includes a drying roller 31 for absorbing the carrier remaining on the photoreceptor belt 10, a regeneration roller 33 for regenerating the absorbed liquid carrier into a vapor carrier by heating the drying roller 31 while rotating in contact with the drying roller 31, and a condenser 35 for condensing the vapor carrier. The carrier condensed by the condenser 35 is stored in a condensation tank 49 which is a constituent of the ink delivery system 40.
Also, a three-way valve 48a disposed in a carrier supply path and having three inlets and one outlet, and a pump 48b, are included in the ink delivery system 40, so that the concentrated ink or carrier accommodated in the ink cartridge 41, the carrier cartridge 43 and the condensation tank 49 is selectively supplied to the circulation tank 44.
The valve 48a and pump 48b operate according to the concentration and volume of the developer liquid contained in the circulation tank 44, sensed by the concentration sensor 45 and/or upper and lower limit level sensors 46a and 46b.
As described above, in the conventional ink delivery system 40 for a liquid electrophotographic printer, when the carrier is used up, the entire carrier cartridge 43 must be replaced.
Thus, to supply the carrier exclusively used for a liquid electrophotographic printer, a user must buy a carrier cartridge as well as an ink cartridge for replacement, which is costly and burdensome.
Also, when the concentrated ink is used up, the entire ink cartridge must be replaced. At this time, functional parts such as an agitator included in the ink cartridge must be replaced as a whole, which raises the cost of the ink cartridge.